﻿GREAT OOLITE. 



39 



In a full-grown Monitor niloticm the distal epiphysis, which affords the articular 

 surface to the astragalus, is unanchylosecl, the line of suture closely resembling that in 

 the distal end of the present fossil. 



Of the foot-bones, " three metatarsals of each foot were secured." The largest 

 appeared to be the first or innermost, the slenderest the third or outermost of the 

 series. " Perhaps there were only three metatarsals, since the specimens we possess 

 exhibit opposite pairs of three and no more" (p. 285). 



That these bones are homologous with those determined as the second, third, and 

 fourth of the pentadactyle foot in Scelidosaurus and Iguanodon I deem more probable 

 than that they answered to the metatarsals of the first, second, and third digits in 

 Crocodilus. 



If a first or a fifth digit existed in the hind foot of Cetiosaurus, their shortness or 

 rudimental condition may have prevented their recognition. 



In the description of the osseous characters then known of the largest species of 

 Whale-Lizard, I remarked : 



" These enormous Cetiosauri may be presumed to have been of aquatic and, most 



Fig. 8. 



Coracoid, Cetiosaurus longus, T \th nat. size. (Phps., part of diagr. xcviii, p. 268.) 



Megalosaurus, but " separated from its base and anchylosed to the tibia ; while in Megalosaurus the con- 

 nection remains, and the ascending process is not joined by synostosis to the tibia" (op. cit., p. 283). 

 Scelidosaurus instructively exemplifies the homology of the distal epiphysis of the tibia in Dinosaurs with 

 that in the .Monitor and the Bird, and demonstrates the separate existence of the bone answering to the 

 astragalus, &c, in both Crocodiles and Lizards, but which is not ossified in the tarsus of Birds. (Monogr. 

 cit., p. 16, pis. x and xi.) 



